4LM6

Light harvesting complex PC612 from the cryptophyte Hemiselmis virescens M1635

4LM6 の概要

• エントリーDOI: 10.2210/pdb4lm6/pdb
• 関連するPDBエントリー: 4LMS 4LMX
• 分子名称: cryptophyte phycocyanin alpha chain, cryptophyte phycocyanin beta chain, PHYCOCYANOBILIN, ... (5 entities in total)
• 機能のキーワード: phycobiliprotein, thylakoid lumen, photosynthesis
• 由来する生物種: Hemiselmis virescens; 詳細
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 54208.14

構造登録者

Harrop, S.J.,Wilk, K.E.,Curmi, P.M.G. (登録日: 2013-07-10, 公開日: 2014-06-18, 最終更新日: 2024-11-06)

主引用文献

Harrop, S.J.,Wilk, K.E.,Dinshaw, R.,Collini, E.,Mirkovic, T.,Teng, C.Y.,Oblinsky, D.G.,Green, B.R.,Hoef-Emden, K.,Hiller, R.G.,Scholes, G.D.,Curmi, P.M.
Single-residue insertion switches the quaternary structure and exciton states of cryptophyte light-harvesting proteins.
Proc.Natl.Acad.Sci.USA, 111:E2666-E2675, 2014

PubMed Abstract: Observation of coherent oscillations in the 2D electronic spectra (2D ES) of photosynthetic proteins has led researchers to ask whether nontrivial quantum phenomena are biologically significant. Coherent oscillations have been reported for the soluble light-harvesting phycobiliprotein (PBP) antenna isolated from cryptophyte algae. To probe the link between spectral properties and protein structure, we determined crystal structures of three PBP light-harvesting complexes isolated from different species. Each PBP is a dimer of αβ subunits in which the structure of the αβ monomer is conserved. However, we discovered two dramatically distinct quaternary conformations, one of which is specific to the genus Hemiselmis. Because of steric effects emerging from the insertion of a single amino acid, the two αβ monomers are rotated by ∼73° to an "open" configuration in contrast to the "closed" configuration of other cryptophyte PBPs. This structural change is significant for the light-harvesting function because it disrupts the strong excitonic coupling between two central chromophores in the closed form. The 2D ES show marked cross-peak oscillations assigned to electronic and vibrational coherences in the closed-form PC645. However, such features appear to be reduced, or perhaps absent, in the open structures. Thus cryptophytes have evolved a structural switch controlled by an amino acid insertion to modulate excitonic interactions and therefore the mechanisms used for light harvesting.

PubMed: 24979784
DOI: 10.1073/pnas.1402538111

実験手法

X-RAY DIFFRACTION (1.7 Å)